Sudden death in the young (SDY) has a devastating impact on families, care providers, and the community, and attracts significant public and media attention. The most common diagnoses that increase risk for SDY include hypertrophic cardiomyopathy, coronary artery anomalies of wrong sinus origin, arrhythmogenic right ventricular cardiomyopathy, ion channelopathies, and genetic forms of epilepsy such as Dravet Syndrome. In up to 30% of cases of SDY, no specific diagnosis is found (autopsy negative). Sudden cardiac death (SCD) has been documented at all ages and may be associated with competitive athletics. Approximately 10-15% of sudden infant death syndrome (SIDS) cases may be due to ion channelopathies. Similarly, sudden unexpected death in epilepsy (SUDEP) has been documented at all ages, and several risk factors have been identified, including some cases originating with ion channelopathies. Noncompliance of antiepileptic medication usage and polytherapy in patients with refractory epilepsy are also risk factors for SUDEP. The Sudden Death in the Young (SDY) Initiative is a two-phase program to explore and provide greater understanding of SDY. The second phase of the program will support scientific research through the use of the registry data and DNA samples using the NIH grant mechanism. The second phase of the program will run concurrently with the SDY Registry.